n loss-in-weight feeder devices or batchers where a shaft rotates operating a helical screw to discharge dry comminuted materials, maintaining a seal so that the dry materials do not leak past the shaft bearing is a problem. The current devices used to prevent such leakage from happening involve a friction type seal such as an `O` ring or a lip seal, etc., in a non-lubricated environment on the dry material side of the container. The seal is fixed in the housing and the shaft rotates in the seal against the sealing surface. Due to high friction and the absence of a lubricant, seal wear is excessive due to abrasion and heat build up. This ultimately leads to premature seal failure (in some cases only a few days) which then allows the material to leak out of the container. The result is increased maintenance cost and degraded system reliability.